Pleiades outfits very durable

Gagaran’s indignant retort was accompanied by a kick at the maid, who was seeking to close into melee combat. That kick was also intended to create some space between them.
The startling thing was that when the greave made contact with the maid uniform, there was a sound of metallic collision.
Gagaran backed off, and the other two members of Blue Rose kept their distance from the maid, forming up while staying wary of area attacks.
“POkiNg hERe anD PoKInG theRE... wHaT a PAiN!”
As Gagaran inspected the maid’s buzzing jaws, her low voice filtered into Evileye’s ears.
“Did you hear that? That maid uniform’s as hard as my weapon, what a joke.”
“It’s woven from a very hard metal. Given its thickness, I’d say her clothes are much harder than your weapon.”
“Adamantite... no, that’s not it.”
“I don’t think that’s all, no? She’s got gear so good that it doesn’t even make sense... My earth-elemental spells aren’t too effective against her. In other words, her items must include something with the effect of reducing magical damage. Simply put, finding her weakness and taking her unawares isn’t going to be too effective.”

- Overlord; Vol 6; Chapter 9